Menchaca-Rocha and his colleagues are following in the footsteps of the late Luis Alvarez, a Nobel physics laureate from the University of California, Berkeley. In the late 1960s, Alvarez placed muon detectors in a tunnel beneath the Great Pyramid of Chefren in Egypt in search of hidden burial chambers. None were discovered.

Another speaker at the meeting, Kanetada Nagamine of the KEK Muon Science Laboratory in Japan, reports on his team's use of cosmic-ray muons to essentially take X-rays of the interior of volcanoes for hints of their eruption potential. Nagamine and his colleagues exploit the fact that some high-energy muons are traveling almost horizontally when they reach Earth's surface. By placing multiple muon detectors around a mountain, the scientists can measure its shape and look for interior channels where molten rock may be rising, an early sign of a potential eruption. The research team has studied several volcanoes in Japan, including as assessment of the amount of molten rock within the crater of Mt. Asama.

Closer to home, scientists at Los Alamos National Laboratory in New Mexico have been exploring the use of muon radiography to detect illicit nuclear materials in cargo containers or trucks. Existing X-ray devices, already being deployed at ports and border crossings, cannot readily detect a well-shielded cache of highly enriched uranium, material that could be used in a devastating nuclear bomb. Newer scanning methods, using either dual-beam X-rays or neutrons, can pose radiation hazards to security personnel or illegal immigrants who might stow away in a container.

The muon detection method would involve passive monitoring of vehicles and cargo containers, with no artificial dose of radiation involved, according to the Los Alamos researchers. Truck drivers could remain in their vehicles while the scan is underway. "We measure the angle of a muon coming in
'"/>


19-Feb-2005